1. Field of Use
The invention comprises a resettable thermo/electric circuit breaker of a type utilizing a single-contact break supported by a U-shaped bimetallic thermal sensing element.
2. Description of Related Art
Circuit breakers utilizing a double-contact break supported by a U-shaped bimetallic thermal sensing unit are widely used in electric circuits to prevent current overload. Examples of this type of prior art circuit breaker, all of which are assigned to the assignee of this invention, include the Series 02 circuit breaker depicted in FIG. 9 and inventions disclosed in U.S. Pat. Nos. 2,513,564; 2,514,545; and 2,689,895. Because of the relatively high contact resistance associated with the two pairs of contacts utilized in these designs, they are susceptible to intermittent loss of electrical continuity for applications involving low open circuit voltage. Each time the circuit breaker contacts are opened and reclosed, a new and unique contact interface is formed which can alter the contact resistance. Prior art designs use high contact force to elastically and plastically deform microscopic protrusions present on the contact surfaces. The resulting larger contacting area provides a lower contact resistance, but this is not always sufficient to preclude the occurrence of intermittent continuities within the circuit breaker.